Polyamideimide and polyamide amic acid resin polymers (hereinafter referred to as PAI) are well-known thermally stable polymers that are used for many high performance coating applications due to their excellent adhesion, temperature resistance, and high strength.
A typical route to synthesizing polyamideimide polymers in a form that is convenient for the manufacture of coatings includes reacting diisocyanate, often 4,4′-methylene diphenyldiisocyanate (MDI) with trimellitic anhydride (TMA). In this process, PAI polymers are typically manufactured in polar aprotic solvents such as N-methyl amide compounds, including, but not limited to, dimethylformamide, dimethylacetamide, N-methylpyrrolidone (NMP), or N-ethylpyrrolidone.
However, with increasing regulation of certain materials and compounds, the solvents used in these polymerizations have recently come under scrutiny due to toxicological concerns.